Two recently discovered electrophysiological phenomena prompt this proposal. First, a brief sound stimulus evokes a regular series of waves from the human brainstem which can be extracted from the raw EEG by computer techniques. Second, a continuous tonal signal evokes an electrical response of the same frequency from these same brainstem structures, and this can similarly be extracted from the EEG. Each of these sound-induced brain signals can be detected with ease in children regardless of whether they are awake or asleep. We present here a plan to use these brain signals for audiometric testing and diagnosis in children. We propose both to use existing conventional laboratory equipment with the goal of developing new brainstem audiometric tests and defining their limitations, and to fabricate a portable device to replace the cumbersome laboratory equipment now needed; this machine will permit making the necessary measurements in places and upon patient populations not now readily accessible.